This invention relates to 1-methyl-4-(2-carboxythioxanthen-9-ylidene)piperidine as an appetite stimulant and antihistamine with low antiserotonin and anticholinergic activity for the treatment of histaminically induced allergies; also contemplated within the scope of the present invention are pharmaceutically acceptable salt; ester and amide derivatives thereof. Further, this invention relates to processes for the preparation of such compounds; to pharmaceutical compositions comprising such compounds; and to methods of treatment comprising administering such compounds and compositions when an appetite stimulant or antihistamine is indicated. The free acid form of the 1-methyl-4-(2-carboxy-thioxanthen-9-ylidene)piperidine of the present invention has the following structural formula (I): ##STR1##
Accordingly, it is an object of the present invention to provide 1-methyl-4-(2-carboxy-thioxanthen-9-ylidene)piperidine and its pharmaceutically acceptable salt, ester and amide derivatives as appetite stimulants and antihistamines. It is a further object of this invention to provide processes for the preparation of such compounds; pharmaceutical compositions comprising such compounds; and methods of treatment comprising administering such compounds and compositions when an appetite stimulating or antihistaminic effect is indicated.